Improve the Crosslinking Reactivity of Nitrile: Design of Nitrile-Functionalized Pyrazine and its Hydrogen Bond-Assisted Nucleophilic Enhancement Study.

In this study, molecular engineering and biomimetic principles are utilized to prepare highly effective nitrile-functionalized pyrazine crosslinking units by exploiting pyrazine's unique nucleophilic strengthening mechanism and proton bonding ability. The curing behaviors of pyrazine-2,3-dicarbonitrile and phthalonitrile are investigated through model curing systems and molecular simulation. The results indicate that pyrazine-2,3-dicarbonitrile exhibits higher reactivity than phthalonitrile, promoted by amine. The cured products of pyrazine-2,3-dicarbonitrile predominantly comprise thermally stable azaisoindoline and azaphthalocyanine. This novel type of highly effective crosslinking unit, and the comprehended mechanism of action of pyrazine at the molecular level, significantly expand the application of pyrazine in materials science.

Biomineralization-Inspired Confined-Space Fabrication of Polyimide Aerogels.

The biomineralization process endows biominerals with unique hierarchically porous structures and physical-chemical properties by filling the restricted microreaction space with amorphous phases before the growth of inorganic crystals. In this paper, a confined-space fabrication method inspired by biomineralization for preparing hierarchically porous polyimide (PI) aerogels and PI-derived carbon aerogels is introduced. The confined structure is established through a self-assembly method of vacuum impregnation and ultrasound-assisted freeze-drying. The hierarchically porous structure is controlled by adjusting the structure characteristics of the confined space and secondary aerogels. Subsequently, a variety of performance demonstrations are conducted to demonstrate the mechanical properties and application prospects in the fields of thermal insulation and electromagnetic shielding of the prepared aerogel.